PYROLYSIS OF YALLOURN COAL IN A POWDER PARTICLE FLUIDIZED-BED

The pyrolysis of Yallourn brown coal in helium in a powder-particle fluidized bed was conducted at ambient pressure, with continuous coal feed and char recovery. The effects of the operating conditions and the kind of fluidizing particles (CaO, activated alumina, silica sand and porous silica) on the yields of hydrocarbon gas and liquid were examined. Under the experimental conditions, the product composition was strongly affected by the pyrolysis temperature and the kind of fluidizing particles. The effect of silica sand on the secondary reactions of volatile matter was quite small, whereas CaO and activated alumina particles showed high activity for the cracking of volatile matter. At 800-degrees-C, BTX yields were considerably reduced by CaO and activated alumina. On the other hand, at 600-degrees-C the yields of both hydrocarbon gas and liquid with CaO and activated alumina were higher than those with silica sand. The hydrocarbon gas and BTX yields could be increased by using an active catalyst under appropriate pyrolysis conditions even under an inert gas atmosphere.